A standard trough-type conveyor for bulk material has a trough having an intake of generally the same large transverse width as the outlet of the supply hopper or silo and opening upward underneath this outlet for receiving bulk material therefrom. In addition the trough has an output opening downward at the output location, a base extending in the direction, and a pair of side walls extending upward from the base and also extending in the direction. These side walls are normally vertical and spaced apart by the wide transverse dimension of the supply outlet so that material can fall unimpeded from the supply directly into the trough. An endless conveyor chain carrying transversely projecting pushers has an upper stretch immediately juxtaposed in the trough with the base thereof and a lower stretch extending beneath the trough. The chain is driven so its upper stretch advances in an upstream-to-downstream transport direction to move the material from the intake to the outlet of the trough.
As a result of the necessity of making the conveyor trough as wide as the supply outlet, to prevent arches from forming or the material from otherwise jamming at the intake, the entire machine is fairly bulky. This is particularly disadvantageous since such a conveyor is rarely if ever called upon to move the bulk material at a rate (volume or mass per unit of time) sufficiently great to actually need this large cross section. As a result such a conveyor is normally run at very low speed. This is very disadvantageous as it means that a large mass of the bulk material must be moved for what is often a very low throughput.
Another disadvantage of the known conveyors is that they are very difficult to accurately control. Determining just how much material is being moved and controlling it accurately is very difficult in view of the large mass being displaced and the low advance speed of the conveyor chain.